Low-Temperature Resistivity in a "Giant" Moment Alloy

Resistivity measurements have been made on a dilute alloy of 0.07 at.% Co in Pt in the temperature range of 1.0 to 20^∘{}K. We find that the net resistivity, ρalloy-ρpurePt, is linearly proportional to +lnT in this temperature range, in accordance with Kondo's s-d exchange scattering theory when the effect of ordinary scattering is taken into account. We also find that the net resistivity is linearly proportional to 〈μeff(T)〉², where μeff(T) is the effective moment associated with the Co impurity and surrounding Pt electrons, which decreases at lower temperatures, as deduced from Pt¹⁹⁵ nuclear-magnetic-resonance linewidth measurements in the same system. This kind of behavior is predicted by Knapp's two-band model.